Obesity affects more than 30% of adult Americans. In addition, nearly one-quarter meet criteria for the metabolic syndrome, which increases their risks of type 2 diabetes and cardiovascular mortality. The loss of 5% or more of initial weight, combined with increased physical activity, significantly reduces the risk of developing type 2 diabetes and ameliorates the metabolic syndrome and its individual components (i.e., elevated waist circumference, blood pressure, glucose or triglycerides;decreased HDL cholesterol). The benefits of weight loss have been demonstrated principally in efficacy studies conducted at academic medical centers. Interventions have provided intensive treatments (generally without concern for cost) that typically could not be delivered in primary care practice or afforded by most individuals seeking weight loss. The goal of this study is to improve the management of obesity in primary care practice by enlisting office-based physicians and auxiliary health providers (such as nursing assistants) who will be trained to provide weight management. A total of 360 overweight and obese persons at 9 primary care practices in the University of Pennsylvania Health System will be randomly assigned to one of three 2-year interventions: 1) Minimal Care;2) Brief Lifestyle Counseling;or 3) Enhanced Brief Lifestyle Counseling. Each site, following a 1-year study initiation training, will enroll 40 individuals with a BMI >27 kg/m2 plus two or more components of the metabolic syndrome. Participants in the Minimal Care condition (N=120) will receive educational materials distributed by a primary care provider (PCP) at approximately quarterly visits. In addition to quarterly PCP visits, participants in the Brief Lifestyle Counseling condition (N=120) will have 12 brief (10 minutes) visits during the first year with an auxiliary health provider (e.g., nursing assistant) who will review participants'progress in consuming a 1200-1500 kcal/d diet and walking 180 minutes/week. Twelve additional contacts, on-site or by telephone, will be provided the second year. Participants in the Enhanced Lifestyle Counseling condition (N=120) will receive the same intervention as those in the second group. However, they also will be given the choice of using either meal replacements or a weight loss medication to facilitate the induction and maintenance of weight loss. The study's principal hypothesis is that participants in the Enhanced Lifestyle group will achieve significantly greater reductions in BMI, at 1 and 2 years, than will persons in the Brief Lifestyle Counseling condition, which, in turn, will be superior to Minimal Care. A similar pattern of findings is anticipated in the resolution of the metabolic syndrome (and its individual components). Secondary analyses will compare changes among groups in mood, quality of life, and sexual function. Costs and patient satisfaction associated with the three interventions will be determined. This study holds promise of identifying effective weight loss methods that can be provided in primary care, at reasonable cost, by existing office personnel.